1. Field of the Invention
The present invention relates to a laminated sheet having electromagnetic wave shielding effects and to a manufacturing method therefor. This application is based on patent application No. Hei 9-10695 filed in Japan, the content of which is incorporated herein by reference.
2. Description of the Related Art
Many electronic devices generate electromagnetic waves and these waves cause problems such as the faulty operation of neighboring devices. For this reason, molded products manufactured using resins which contain conductive materials such as metal powder, carbon black, and the like; molded resin products which have been coated with conductive paint; or products which have been plated are used as housings for electronic devices.
However, with regard to these types of molded products having electromagnetic wave shielding effects, there are problems such that those molded products which have good electromagnetic wave shielding properties have low transparency, while, on the other hand, those molded products which do have high transparency have electromagnetic wave shielding properties which are not satisfactory. In addition, there are also problems in that the fitting of earths, for the purpose of grounding, to molded products having electromagnetic wave shielding effects is difficult, and the process of attaching the earth is complicated.
In addition, as a method for manufacturing a laminated sheet which has transparency and electromagnetic wave shielding effects, a manufacturing method (Japanese Patent Application, First Publication, No. Hei 8-183132) has been proposed in which a thermoplastic resin sheet and a mesh-like sheet are laminated to obtain a laminated sheet by means of using a laminating film.
However, in this method, since a laminating film (having a thickness of 12xcx9c50 microns, for example) which is thinner than the conductive mesh-like sheet is used, there are problems in that attention must be given to the prevention of the collection of dust on the laminating film, to the fact that it is easy for bubbles to remain at the interface between the laminating film and the thermoplastic resin sheets, and to the prevention of wrinkling of the laminating film. In addition, since a methacrylic resin (PMMA) sheet is used as the thermoplastic resin sheet, the laminated sheet has the problem that it is lacking in flexibility.
Consequently, the present invention provides a laminated sheet which has a combination of both transparency and electromagnetic wave shielding properties, and which can be manufactured easily without the use of a laminating film like that mentioned above. In addition, the present invention provides a manufacturing method for this laminated sheet. In addition, it is an object of the present invention to provide a laminated sheet for which it is possible to easily connect an earth to a desirable position of the laminated sheet, and to provide a manufacturing method for this laminated sheet.
Furthermore, another object of the present invention is the provision of a laminated sheet having electromagnetic wave shielding effects, which can be readily cut to the required size, and on which post-processing, such as heat adhesion, ultrasonic adhesion, solvent adhesion or the like, can be easily conducted.
The above-mentioned problems can be solved by a laminated sheet comprising a conductive mesh and at least one thermoplastic resin layer, wherein a part of the conductive mesh is imbedded in the above-mentioned thermoplastic resin layer, and a part of the intersecting points which are a part of the elements making up the conductive mesh are exposed from the above-mentioned thermoplastic resin layer.
In addition, the above-mentioned problems can be solved by means of a laminated sheet in which one side of a conductive mesh is imbedded in a thermoplastic resin layer, wherein the thickness of the above-mentioned thermoplastic resin layer is two times or greater than the thickness of the conductive mesh, and the other side of the conductive mesh is divided into a section which is imbedded within the thermoplastic resin layer and covered by resin and a section in which a part of the conductive mesh is not imbedded in the resin layer and which is exposed from the above-mentioned thermoplastic resin layer.
The laminated sheet of the present invention can be easily manufactured by means of a manufacturing method in which at least one side of a conductive mesh is imbedded in a resin layer, wherein a conductive mesh-like sheet is positioned on a molding plate, a thermoplastic resin sheet which has a thickness which is two times or greater than the thickness of the conductive mesh-like sheet is positioned on the conductive mesh-like sheet, and a molding plate is positioned on the thermoplastic resin sheet, then, in this condition, the thermosoftened thermoplastic resin sheet and the conductive mesh-like sheet are laminated into a single body.